Application of TiO2 hollow spheres and ZnS/SiO2 double-passivaiting layers in the photoanode of the CdS/CdSe QDs sensitized solar cells for the efficiency enhancement

Abstract

Abstract In this work quantum dot sensitized solar cells (QDSCs) with multilayer photoelectrodes were fabricated and investigated. The co-sensitization was carried out by CdS and CdSe quantum dots (QDs) layers and double passivation was performed by ZnS and SiO2 electron blocking films. Two kinds of TiO2 scaffolds in the forms of transparent TiO2 nanocrystals (NCs) and a double layer TiO2 NCs/TiO2 hollow spheres (HSs) were fabricated and utilized. The main CdSe sensitizing layer was deposited through a fast and effective chemical bath deposition (CBD) method in different conditions. Finally, a wide range of photoanodes were fabricated and applied in a conventional structure of the QDSCs. The results showed the maximized PCE of 3.65% for the QDSC with TiO2 NCs/CdS/CdSe (9\xa0min)/ZnS/SiO2 photoelectrode. This efficiency was enhanced about 65% compared to the reference cell with CdSe and SiO2 free photoanode. For the double layer mesoporous TiO2 sublayer, it was shown that the QDSC with TiO2 NCs/HSs/CdS/CdSe (9\xa0min)/ZnS/SiO2 multilayer photoanode demonstrated the maximum PCE of 6.1%. The mentioned efficiency was increased about 82%, 37% and 31% compared to the corresponding reference cells with TiO2 NCs/HSs/CdS/ZnS and TiO2 NCs/HSs/CdS/ZnS/SiO2 and TiO2 NCs/HSs/CdS/CdSe (9\xa0min)/ZnS photoelectrodes, respectively.